1. Technical Field of the Invention
The invention relates generally to communication systems; and, more particularly, it relates to communication systems employing Reed-Solomon (RS) coding.
2. Description of Related Art
Data communication systems have been under continual development for many years. One such type of communication system that has been of significant interest lately is a communication system that employs iterative error correction codes. One type of communication system that has received interest in recent years has been one which employs Reed-Solomon (RS) codes (one type of iterative error correcting code). Communications systems with iterative codes are often able to achieve lower bit error rates (BER) than alternative codes for a given signal to noise ratio (SNR).
A continual and primary directive in this area of development has been to try continually to lower the SNR required to achieve a given BER within a communication system. The ideal goal has been to try to reach Shannon's limit in a communication channel. Shannon's limit may be viewed as being the data rate to be used in a communication channel, having a particular SNR, that achieves error free transmission through the communication channel. In other words, the Shannon limit is the theoretical bound for channel capacity for a given modulation and code rate.
There are a wide variety of applications in which RS codes can be employed to attempt to effectuate (ideally) error free transmission and receipt of information. In the context of communication systems having a communication channel over which coded signals are communicated, RS codes can be employed to attempt to effectuate (ideally) error free transmission from a communication device and/or (ideally) error free receipt of information to a communication device. In the context of hard disk drive (HDD) applications, RS codes can be employed to attempt to effectuate (ideally) error free write and/or read of information to and from storage media. With respect to HDD applications, as is known, many varieties of memory storage devices (e.g. disk drives), such as magnetic disk drives are used to provide data storage for a host device, either directly, or through a network such as a storage area network (SAN) or network attached storage (NAS). Typical host devices include stand alone computer systems such as a desktop or laptop computer, enterprise storage devices such as servers, storage arrays such as a redundant array of independent disks (RAID) arrays, storage routers, storage switches and storage directors, and other consumer devices such as video game systems and digital video recorders. These devices provide high storage capacity in a cost effective manner.
One of the operations performed in prior art decoding of a RS coded signal is the generation of an error value polynomial (EVP). Prior art RS decoding approaches necessarily require the computing the EVP. For large error correction code (ECC) systems (e.g., t=120), this can take anywhere from 1000 to 7000 clock cycles depending on the amount of ALU parallelism is provided in the decoding device. Additionally, computing the EVP typically requires some additional MUXing which may significantly affects area and speed of design in silicon when implementing an actual communication device capable to perform decoding of a RS coded signal.